They are small (5KW) in terms of load support, noisy, and provide poor fuel consumption performance. Additionally, when set in the 240 Volt output mode, it's only a two wire system (without modification) - so there's no center tap / neutral - and therefore will not support powering your house. Yes, it can be modified - but then you loose the ability to select 3 phase output with the reconnection switch, if memory serves.
In other words, it's not for everyone with normal backup power needs. I have one, and keep it around just in case my diesel genset fails - a backup for my backup.
Depending on where you are, I suspect it shouldn't go for more than a few hundred dollars. Up here in NH, I ended up paying a little more than that for my MEP-017A from GL in Maine.
They are solid circa 1968 generators - and many parts are still around; I bought a brand new carb for mine, still in the box for something like $29.
Not too portable, either; weight is more than 400 pounds. That can be an advantage if you're in an area where people steal things, or a pain if you're always moving it around yourself.
My advice; if you want to power your house, get something more modern. If you want something to run odd stuff like three phase loads and it is cheap enough, then pick up the 017A.